1. Field of the Invention
This invention relates to a conveyance device in which the motion of a chassis is powered using a shape memory alloy.
2. Prior Art Statement
Conveyance devices are generally driven either by energy supplied from the exterior or by mechanical driving power generated by an energy source mounted on the device. The energy is ordinarily supplied as electrical or thermal energy which is converted into kinetic energy by a power mechanism such as a motor or an engine and the kinetic energy is used to drive the chassis of the device.
The power conversion mechanism for converting the electric or thermal energy into mechanical energy is, however, generally relatively large in size and weight and, moreover, is complex in structure. Thus when it is mounted on the conveyance device it disadvantageously makes the device considerably larger.
It is, therefore, difficult to apply the conventional power mechanism to a small conveyance device, a small scale transport operation or the like.
One object of the invention is to provide a conveyance device having a power mechanism enabling thermal energy to be converted directly into mechanical driving power by a simple mechanism, obviating the need for a power mechanism of large size or weight.
This invention realizes this object by providing a conveyance device comprising a chassis, a pair of pulleys consisting of a high-temperature pulley constituted as a heat storage body and a low-temperature pulley rotatably supported on the chassis, a belt made of a shape memory alloy wound around the pulleys and memorizing a shape arcing in the direction opposite to the direction the belt arcs by being wound around the pulleys, and a drive wheel for moving the chassis by rotating power from the pulleys.
The high-temperature pulley constituted as a heat storage body is maintained at a temperature slightly higher than the transformation temperature of the shape memory alloy constituting the belt. When the temperature of the portion of the belt in contact with the high-temperature pulley rises above the transformation temperature, a force arises in this portion of the belt for restoring it to the memorized shape. This force operates to move this portion of the belt in the direction of separating it from the high-temperature pulley. This movement of the belt rotates the pulley and the rotation of the pulley is used to power the motion of the chassis.
The present invention thus enables the conveyance device to be powered very economically by a simple mechanism of a belt wound about a pair of pulleys.
The above and other objects and features of the invention will become more apparent from the following detailed description with reference to the accompanying drawings.